A notice on the Canadian government website says: “We are experiencing system issues that may not allow certain nationalities to apply for an eTA. We are working to resolve this issue. Thank you for your patience.”

So far the issues have affected only Israeli applicants, and British travellers are unlikely to face problems. The government claimed processing times had not been affected, with most eTA applications being approved “within minutes”.

The website urges potential visitors to apply for the permit, which costs £3.40, as soon as possible before a trip.

US citizens and travellers with a valid visa are exempt from the eTA requirement, as are those reaching Canada by land or sea. British travellers with dual nationality are also not eligible for the eTA and encouraged instead to use their Canadian passports.

The application process should take a few minutes via the Government of Canada website (cic.gc.ca), but to apply you must have a valid passport or travel document with you, a credit card and an email address. You can only apply for one person at a time.

The introduction of the eTA brings Canada’s entry requirements in line with those of the United States, which requires visa-exempt visitors to obtain an Electronic System for Travel Authorisation (ESTA) before flying.

Previously, British visitors to Canada could arrive without a visa or permit. However, the Foreign Office said entrants might occasionally need to prove that they had sufficient funds to support their stay.

A government spokesman said the eTAs would allow it to screen all travellers before they entered the country. “The authorisation is electronically linked to your passport and is valid for five years or until your passport expires, whichever comes first. Therefore, you must travel with the passport that you applied for your eTA with.”